Small Form-factor Pluggable (SFP) units are standardized units adapted to be inserted within a chassis. A suite of specifications, produced by the SFF (Small Form Factor) Committee, describe the size of the SFP unit, so as to ensure that all SFP compliant units may be inserted smoothly within one same chassis, i.e. inside cages, ganged cages, superposed cages and belly-to-belly cages. Specifications for SFP units are available at http://www.sffcommittee.com/ie/index.html.
SFP units may be used with various types of exterior connectors, such as coaxial connectors, optical connectors, and various other types of electrical connectors. In general, a SFP unit allows connection between an external apparatus, via a front connector of one of the aforementioned types, and internal components of a host system, for example a motherboard or a backplane leading to further components, via a back interface of the SFP unit. Specification no INF-8074i Rev 1.0, entitled “SFP (Small Form factor Pluggable) Transceiver”, dated May 12, 2001, available at ftp://ftp.seagate.com/sff/INF-8074.PDF, generally describes sizes, mechanical interfaces, electrical interfaces and identification of SFP units.
The SFF Committee also produced specification no SFF-8431 Rev. 4.1, “Enhanced Small Form Factor Pluggable Module SFP+”, dated Jul. 6, 2010. This document, which reflects an evolution of the INF-8074i specification, defines, inter alia, high-speed electrical interface specifications for 10 Gigabit per second SFP+ modules and hosts, and testing procedures. The term “SFP+” designates an evolution of SFP specifications.
INF-8074i and SFF-8431 do not generally address internal features and functions of SFP devices. In terms of internal features, they simply define identification information to describe SFP devices' capabilities, supported interfaces, manufacturer, and the like. As a result, conventional SFP devices merely provide connection means between external apparatuses and components of a host system, the host system in turn exchanging signals with external apparatuses via SFP devices.
Additional signal processing capabilities have been added recently to SFP devices, going beyond their usual connection capabilities. For instance, a SFP device may include re-clocking capabilities, for re-clocking a signal received by the SFP unit, for example a video signal. In the case where the video signal is received via an optical connector, the optical video signal must be transformed into an electrical video signal, prior to being re-clocked. The re-clocking unit integrated in the SFP device re-clocks the received electrical video signal at a specific frequency band.
However, with the emergence in the industry of super high frequency (3-30 GHz) communications systems and very soon extremely high-frequency (30-300 GHz) communication systems, there is a need for a SFP receiving unit adapted for receiving multiple high-frequencies bands optical signals.